JPS6090025A - Spray dryer type waste gas treating method - Google Patents

Abstract

PURPOSE:To enable the treatment of waste gas even at the time of low load such as at the time of starting or stopping, by spraying an absorbent slurry by a spray dryer at the time of high load while spraying an absorbent powder at the inlet of the spray dryer at the time of low load. CONSTITUTION:At the time of usual treatment (at the time of high load), a damper 13 is opened and a feeder 14 is brought to a stop state. An absorbent slurry C is supplied to a spray dryer 4 from a slurry tank 9 and sprayed and mixed in waste gas from flues 11, 12. At the starting or stopping of a boiler 1 (at the time of low load), the supply of the absorbent slurry is stopped and the flue 11 is blocked by the damper 13 while the feeder 14 is operated and the flow speed of the waste gas of the flue 12 is kept and an absorbent powder D is blown into waste gas from an absorbent silo 8 to be premixed with said gas and waste gas is brought into contact with the absorbent. The waste gas issued from the spray dryer 14 enters a dust collector 5 and, after the reaction product and the dust B in the waste gas are removed, treated gas is exhausted from a chimney 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spray dryer type flue gas treatment method.

The conventional spray dryer-type flue gas treatment method uses a wet method in which a slurry of absorbent is sprayed and mixed with flue gas in a spray dryer and reacts in direct contact with the absorbent. Dust in the smoke is removed by a dust collector placed after the spray dryer. For this reason, there are advantages such as no wastewater treatment required, simple equipment, and low construction costs, but on the other hand, a large amount of reaction products are discharged from the spray dryer in a dry state so that they can be removed by a dust collector. , and if the operation is stopped, the spraying of the absorbent slurry must first be stopped, or the absorbent slurry must be replaced with water, then the spraying must be stopped, and then the smoke ventilation must be stopped. Smoke exhaust treatment was not possible at the time of stoppage and stoppage.

Incidentally, since industrial boilers have only a short operating time per year and frequently start and stop, it has been considered that spray dryer-type flue gas treatment methods cannot be used to treat their flue gas.

The present invention was devised in order to solve the above-mentioned conventional problems, and is a spray dryer type exhaust system that allows exhaust smoke to be treated during low loads (starting, stopping) in the same way as during high loads. The purpose is to provide a smoke treatment method.

The present invention will be explained below with reference to FIGS. 1 and 2. FIG. 1 is a system diagram showing an example of a device using the method of the present invention, and FIG. 2 is a schematic cross-sectional view showing the main part configuration of the device. In the figure, 1 is a boiler, 2 is an air preheater for cooling flue gas and preheating boiler combustion air, 3 is a fan for supplying boiler combustion air,
4 is a spray dryer, 5 is a dust collector, 6 is a smoke exhaust fan, F is a chimney, 8 is an absorbent silo, and 9 is a slurry tank. The flue IR is provided with a damper port for blocking smoke exhaust, and the flue ν is provided with a required number of feeders 14 for blowing absorbent.

The feeder 14 includes an absorbent supply pipe 16 having a nozzle 15 at the tip thereof facing in the exhaust gas flow direction at the center of the flue cross section, and an absorbent supply pipe 16 having a nozzle 15 at the tip thereof facing in the flow direction of the exhaust gas. and a compressed air supply pipe having a nozzle 17 inserted concentrically.

In such a flue gas treatment device, the flue gas A from the boiler 21 is cooled by the air preheater 2 and then sent to the spray dryer through the flue 10, where it comes into contact with an absorbent and reacts with it, and then is sent to the dust collector. In step 5, the reaction products and the dust (B) in the flue gas are removed and released and diffused from the chimney to the outside.

In the present invention, during normal processing (high load), the damper 13
At the same time, the absorbent slurry 〇 is supplied from the slurry tank 9 to the spray dryer number, where it passes through the flue 11, and is mixed with the flue gas to be exhausted. Contact reaction occurs between smoke and absorbent. In addition, when the boiler 1 is started or stopped (at low load), the supply of absorbent slurry 〇 to the spray dryer number is stopped, and the flue 11 is blocked at the damper mouth to prevent exhaustion from the flue n. While maintaining the flow rate of smoke, the feeder 14 is operated, and the absorbent powder supplied from the absorbent silo 8 through the absorbent supply pipe 16 into the nozzle 15 is exhausted by the compressed air E from the nozzle 17. By blowing into the absorbent and premixing it, the flue gas and the absorbent are brought into contact with each other.

Water F is supplied to the slurry tank 9, absorbent powder is supplied from the absorbent silo 8, and a mixture of unreacted absorbent, reaction products, and dust in flue gas is collected from the spray dryer E1 dust collector 5. A part of the collected dust (reaction products and dust in flue gas) B is supplied and mixed to create absorbent slurry C. The amount of absorbent powder used in absorbent slurry 0 has been reduced in an effort to recover the amount of absorbent used in absorbent slurry 0, thereby suppressing the overall increase in absorbent consumption.

FIG. 3 is a system diagram showing the other side of the apparatus using the method of the invention. In the figure, parts that have the same functions and effects as those of the device shown in FIG. 1 and FIG. A recycled ash silo 19 is provided between the absorbent silo 8 and the absorbent silo 8, and contains the absorbent powder from the absorbent silo 8, the mixture E from the spray dryer, and a part of the collected dust (B) from the dust collector 6. The mixture G is then supplied to the feeder 14 and the slurry tank 9, respectively, and the dust collected by the spray dryer and the dust collector 6 is added to the absorbent powder supplied to the feeder 14.
BS1! ! This invention is based on the fact that the collected dust is circulated in order to reduce absorbent consumption during low loads by mixing it with Since it is configured to be usable, the disadvantages of the spray dryer type flue gas treatment method are eliminated, and the advantages of this treatment method can be fully utilized when used for, for example, flue gas treatment from an industrial boiler.

In addition, in order to use the spray dryer type flue gas treatment method for flue gas treatment during low loads, it is sufficient to incorporate a simple device such as a feeder as shown in the example, so there is no problem with the ease of use of this treatment method. Not damaged.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an example of a device using the method of the present invention, Fig. 2 is a schematic sectional view showing the configuration of the main parts of the device, and Fig. 3
The figure is a system diagram showing the other side of the design using the method of the invention. 1... Boiler? ...Air preheater, 3.6...Fan, 4...Spray dryer, 5...Dust collector, 1
... Chimney, 8 ... Absorbent silo, 9 ... Slurry tank, 1O1n112 ... Flue, edict ... Damper, 1
4... Feeder, 15.17... Nozzle, 16.
...Absorbent supply pipe, 18...Compressed air supply pipe, 19.
...Recycled ash silo. Procedural amendment (method) March 2, 1980 Director General of the Patent Office ■ 1972 Patent Application No. 197275 2 Title of invention Spray dryer type flue gas treatment method 3 Relationship with the case of the person making the amendment Patent application Person 4, sub-agent

Claims (1)

[Claims] At high loads, the absorbent slurry is sprayed and mixed into the flue gas using a spray dryer, and at low loads, absorbent powder is blown into the flue gas at the inlet side of the spray dryer and mixed in advance. A spray dryer type flue gas treatment method characterized by causing a contact reaction between flue gas and an absorbent to remove sulfur compounds in the flue gas, and then using a dust collector to remove reaction products and dust in the flue gas.